"""
单例模式
"""


class Student:
    __instance = None

    def __new__(cls, *args, **kwargs):
        if None is cls.__instance:
            cls.__instance = object.__new__(cls)
            return cls.__instance
        else:
            return cls.__instance


s = Student()
s1 = Student()
s2 = Student()

print(s)
print(s1)
print(s2)
